MEGACO is a recently adopted standard (control protocol) for controlling Media Gateways (MGs) via Media Gateway Controllers (MGCs). MEGACO makes use of IP addresses explicitly contained within control messages exchanged between MGs and MGCs. Network Address Translation (NAT) is the act of changing an IP address from one IP network realm to another IP network realm where the IP networks are separated by a firewall/router. NAT is employed for such reasons as security, ease of network configuration, and a lack of IP addresses. Thus, in a configuration of two different IP networks separated by a firewall/router, NAT is used to ensure that IP packets reach their intended destinations. MEGACO currently will not function properly across different IP networks, however, because the IP addresses embedded in MEGACO messages are not subjected to NAT.
What is needed is a mechanism for allowing the firewall/router separating the IP networks to inspect and translate the IP addresses within MEGACO message packets during the NAT procedure. Such a mechanism would allow an MGC in one IP network to control an MG in another IP network.